Silicon dioxideSilicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as a synthetic product. Notable examples include fused quartz, fumed silica, silica gel, opal and aerogels. It is used in structural materials, microelectronics (as an electrical insulator), and as components in the food and pharmaceutical industries.
TridymiteInfobox mineral | name = Tridymite | category = Oxide mineral (or tectosilicate), quartz group | boxwidth = | boxbgcolor = | image = Tridymite tabulars - Ochtendung, Eifel, Germany.jpg | imagesize = 260px | caption = tabular tridymite crystals from Ochtendung, Eifel, Germany | formula = SiO2 | molweight = 60.08 g/mol | strunz = 4.DA.10 | IMAsymbol = Trd | system = Orthorhombic (α-tridymite) | class = Disphenoidal (222) H–M symbol: (222) | symmetry = C2221 | color = Colorless, white | habit = Platy – sheet forms | cleavage = {0001} indistinct, {1010} imperfect | fracture = Brittle – conchoidal | mohs = 7 | luster = Vitreous | refractive = 'nα=1.
CristobaliteCristobalite (krɪˈstoʊbəˌlaɪt) is a mineral polymorph of silica that is formed at very high temperatures. It has the same chemical formula as quartz, SiO2, but a distinct crystal structure. Both quartz and cristobalite are polymorphs with all the members of the quartz group, which also include coesite, tridymite and stishovite. It is named after Cerro San Cristóbal in Pachuca Municipality, Hidalgo, Mexico. It is used in dentistry as a component of alginate impression materials as well as for making models of teeth.
Second-harmonic generationSecond-harmonic generation (SHG, also called frequency doubling) is a nonlinear optical process in which two photons with the same frequency interact with a nonlinear material, are "combined", and generate a new photon with twice the energy of the initial photons (equivalently, twice the frequency and half the wavelength), that conserves the coherence of the excitation. It is a special case of sum-frequency generation (2 photons), and more generally of harmonic generation.
Nonlinear opticsNonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear.
Silicon nitrideSilicon nitride is a chemical compound of the elements silicon and nitrogen. Si3N4 (Trisilicon tetranitride) is the most thermodynamically stable and commercially important of the silicon nitrides, and the term ′′Silicon nitride′′ commonly refers to this specific composition. It is a white, high-melting-point solid that is relatively chemically inert, being attacked by dilute HF and hot H3PO4. It is very hard (8.5 on the mohs scale). It has a high thermal stability with strong optical nonlinearities for all-optical applications.
Optical computingOptical computing or photonic computing uses light waves produced by lasers or incoherent sources for data processing, data storage or data communication for computing. For decades, photons have shown promise to enable a higher bandwidth than the electrons used in conventional computers (see optical fibers). Most research projects focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data.
